EATING genetically modified (GM) food could give you cancer. That is the stark warning today from one of Scotland's leading experts in tissue diseases.

Dr Stanley Ewen, a consultant histopathologist at Aberdeen Royal Infirmary, says that a cauliflower virus used in GM foods could increase the risk of stomach and colon cancers.

He is calling for the health of people who live near the farm-scale GM crop trials in Aberdeenshire, Ross-shire and Fife to be monitored. Their food and water will be contaminated by GM material, he said, which could hasten the growth of malignant tumours.

'I don't want to be scare-mongering, I want to be understated,' Ewen told the Sunday Herald. 'But I'm very concerned that people who rely on local produce might be endangering themselves.'

The government, backed by its scientific advisors, has always insisted the GM trials pose no risk to human health or the environment. Nevertheless, the trials have provoked widespread opposition, with dozens of protesters arrested for damaging GM crops.

Ewen's warning, which has been delivered to the Scottish Parliament's Health and Community Care Committee, is bound to be seized on by critics . The committee is just completing an investigation into the safety of GM food and is hoping to report its findings this week.

Ewen, who has 29 years' experience as a histopathologist, is currently leading a pilot project in Grampian to screen people for colon cancer. In 1999, along with Dr Arpad Pusztai, a former researcher at Aberdeen's Rowett Institute, he published a study suggesting that GM potatoes harm rats.

In his submission to the health committee, Ewen expressed 'great concern' about the use of the cauliflower mosaic virus as a 'promoter' in GM foods. The virus is used like a tiny engine to drive implanted genes to express themselves.

But Ewen pointed out that the virus is infectious, and could act as a 'growth factor' in the stomach or colon, encouraging the growth of polyps. The faster and bigger polyps grow, the more likely they are to be malignant, he added.

There are also risks in feeding GM products like maize to cattle, he cautioned.
'It is possible cows' milk will contain GM derivatives that can be directly ingested by humans as milk or cheese. Even a lightly cooked, thick fillet steak could contain active GM material.'

GM material can be destroyed by cooking or boiling for 10 minutes, and it can be broken down by the acids and enzymes in the stomach. But Ewen is worried that genes in uncooked GM fruit and vegetables could survive common stomach infections.

'It is possible GM DNA could affect stomach and colonic lining by causing a growth factor effect with the unproven possibility of hastening cancer formation in those organs,' he stated.

Ewen stressed that he is not opposed to all GM technology, which he believes could have real benefits, particularly in medicine. But he is sufficiently alarmed by the current use of the technology to urge the health committee to call for a ban on GM crop trials while their safety is tested on animals.

Doctors from the British Medical Association have also suggested a GM ban to the committee because of the unknown effects on health. The committee's investigation was prompted by a petition of 6000 signatures gathered by protesters who maintained a vigil at a GM trial site at Munlochy in Ross-shire.

'What is most worrying about Dr Ewen's evidence is that while his concerns are disease-specific, the risks extend to a wide range of GM food crops,' said Jo Hunt, director of the lobby group Highlands and Islands GM Concern.

'The effects are caused not by just one 'bad' DNA fragment, but are a result of the reaction of plant cells to genetic engineering itself. All the major GM food plants currently produced could have the same effect when eaten.'

Hunt argued that long-term research was needed to establish whether GM food was safe. 'But instead of looking at the impact of GM food on people's health, the Scottish Executive has spent over £5 million on farm-scale trials to see how growing GM crops on Scottish farms will affect butterflies and weeds. The Executive has already released GM at 11 sites and is considering allowing GM to be released anywhere in the country from 2004, before it knows whether GM food is safe to eat.'

The Executive also came under fire from the Scottish National Party's shadow environment minister, Bruce Crawford, who demanded a freeze on GM crops trials. 'We cannot allow GM material to enter the food chain until there are absolute guarantees that there are no risks,' he said.

He pointed out that, in a recent letter, the environment minister, Ross Finnie, had admitted to him that plants around GM crops could become contaminated. Finnie added, however, that the government's advice was 'unanimous in its conclusion that GM crops that have approval do not pose a safety threat.'

Ewen's evidence to the health committee is backed up by a separate submission from Arpad Pusztai, who now works as an independent consultant. He warned that GM contamination could jeopardise human health and cause irreversible environmental damage.

'We need to rethink the whole strategy of genetic engineering,' Pusztai said. 'Because of its potential importance for, and effect on, mankind, it should not be left to the decision of a few multinational companies.'